Link guide mechanism for externally powered automatic guns



Nov. 1, 1966 J. G. ROCHA 3,282,163

LINK GUIDE MECHANISM FOR EXTERNALLY POWERED AUTOMATIC GUNS Filed May 18, 1965 5 Sheets-Sheet 1 INVE NTOR John [3.Rnch11 ATTORNEYS NOV. 1, 1966 oc 3,282,163

LINK GUIDE MECHANISM FOR EXTERNALLY POWERED AUTOMATIC GUNS Filed May 18, 1965 5 Sheets-Sheet 2 FI L INVENTOR ATTORN Nov. 1, 1966 RQCHA 3,282,163

LINK GUIDE MECHANISM FOR EXTERNALLY POWERED AUTOMATIC GUNS Filed May 18, 1965 5 Sheets-Sheet 5 INVENTOR J 01111 ELRnnhu TV i1 ATTOR'NEYS United States Patent LlNK GUIDE MECHANISM FOR EXTERNALLY POWERED AUTGMATIC GUNS John G. Rocha, Westfield, Mass, assignor to the United States of America as represented by the Secretary of the Army Filed May 18, 1965, Ser. No. 456,872

5 Claims. (Cl. 89-33) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to automatic guns in which the barrel is actuated forwardly to open the breech and is returned to the battery position thereof to chamber the leading cartridge in a flexibly linked belt. It is more particularly directed to improved means for controlling the movement of the leading cartridge in the belt during passage to the chambering position thereof.

In automatic guns which are operated by an externally powered variable-speed motor, it is essential that the ammunition therefor be fed into firing position in positive synchronization with the opening and closing of the breech. This requirement has been satisfactorily achieved in certain guns of recent military design by the inclusion of a cylindrical drum operatively connected to the motor and provided with individual cam tracks for actuating the barrel and the feeding mechanism. In this arrangement, rotation of the drum reciprocates the barrel to open and close the breech and simultaneously actuates the feed mechanism to advance the cartridge belt into the feedway of the gun during the interval in which the barrel is out of battery position at a distance greater than the length of a cartridge.-

Although the leading cartridge in the belt is adequately guided across the feedway by a narrow channel formed in the floor surface thereof in position to slidably receive a portion of the annular rim at the rear end of each incoming cartridge, relatively serious feeding jams have nevertheless been encountered from time to time, especially when the gun is being operated in the upper regions of its variable firing rate. Analysis of these malfunctions indicates that' the causative factor is the lack of any positive restraint on the leading cartridge against vertical bouncing in the feedway and against axial rolling about the longitudinal axis thereof within the extent permitted by the flexibility ofthe connection between adjacent links.

Accordingly, the configuration of the cartridge belt links was modified to provide linear sections at the top and bottom thereof spaced apart at substantially the same distance as the height of the transverse feedway in the receiver to permit slidable passage therethrough. While this change in the design of the links successfully eliminated execessive vertical movements of the leading cartridge during the passage thereof through the feedway, the complete elimination of feeding jams has not yet been achived primarily due to the necessity for a shallow longitudinal trough which is centrally formed in the floor of the feedway to accommodate the peripheral contour of the underside of the barrel. Inasmuch as this trough is directly opposite the longitudinal slot provided through the top of the feedway for passage of the locking lug projecting upwardly from the breech end of the barrel, the cartridge belt link on the leading cartridge cannot be adequately controlled at the critical period when such "ice cartridge is being advanced to the position required for the chambering thereof by the return stroke of the barrel. Consequently, in the event the linear sections of the link on the cartridge being chambered are appreciably tilted out of parallel alignment with the upper and lower surfaces of the feedway at the time the barrel begins to force such link rearwardly along the cartridge, there is a strong possibility that the link will bind in the feedway and create a relatively dangerous feeding jam.

Efforts to eliminate this undesirable axial rolling .of the leading cartridge in the feedway have heretofore met with little or no success. For example, it was proposed that the shallow trough in the floor of the feedway be eliminated in order to provide a continuous level surface which would prevent any tilting of the cartridge belt link. However, while this solution did exert the required control over feeding travel of the link on the leading cartridge, the benefits thereof were completely outweighed by the tendency for the barrel to split at the breech end thereof as a result of the reduction in the wall thickness thereof produced by the removal of the peripheral contour on the underside thereof previously accommodated by the shallow trough in the feedway floor.

It is therefore a general object of this invention to provide improved means for controlling the passage of the leading cartridge in a linked belt through the transverse feedway of an externally powered gun of the type wherein the barrel is continuously reciprocated to successively chamber each cartridge in the belt.

It is a further object of the present invention to provide the aforesaid cartridge link control means without interference with the critical timing relationship required between the feeding movement of the cartridge belt and the reciprocal travel of the barrel.

Another object of this invention is to provide a pair of pivot-a1 guide members in the cartridge belt feedway of a gun .as aforesaid so that the members can be pivoted into the feeding path of the cartridge belt and out of the counter-recoil path of the barrel without the utilization of any springs.

An final object of the present invention is to provide a link control mechanism as aforesaid which will function in the same positive manner regardless of the radial position of the gun relative to the horizontal or regardless of the angle at which the gun is being operated.

It has been found that these objects can best be achieved by a pair of relatively thin guide members pivotally mounted at one end thereof at opposite locations in the floor and ceiling of the transverse feedway in the receiver. Each guide member is provided with a vertical shoulder disposed in feeding path of the link on the leading cartridge in the belt. Thus, as such cartridge is advanced into'the feedway the link thereon pivots the guide members to form a bridge over the longitudinal interruptions formed along the central areas of the feedway floor and ceiling in order to accommodate the configuration of the barrel at the breech end portion thereof. In the bridging position of these guide members, the forward edges thereof are disposed in the rearward path of the barrel in the position to be pivoted outwardly thereby. Both guide members are thus returned to the original position thereof in which the vertical shoulders thereon are disposed in the feed path of the link on the leading cartridge of the belt. The foregoing arrangement provides a simple and economical means for guiding the link on the leading cartridge in a belt across any recesses or openings in the floor and ceiling of a cartridge belt '3 feedway without incurring any interruptions or misalignments in the feeding travel of the cartridge belt and in the reciprocation of the barrel.

Further objects and advantages of the invention will be apparent from the following specification and the accompanying drawings which are for the purpose of illustration only and in which:

FIG. 1 is an elevationalview of the entrance end of a cartridge belt feedway in an externally powered gun to which the present invention is particularly applicable;

FIG. 2 is a vertical section taken along line 22 in FIG. 1 to show the relationship of the link guide members to the leading cartridge in the linked belt immediatelyprior totheopening of the breech;

FIG. 3 is a lateral section taken along line 3-3 in FIG. 2 to show the link guide member in the floor of the feedway in position to contact the link on the incoming cartridge, the barrel being shown in phantom in the battery position thereof;

FIG. 4 is a view similar to FIG. 3 but with the link guide member thereof being shown in the position imparted thereto by the link on the incoming cartridge (illustrated in phantom outline) when the barrel is in the forwardmost position thereof;

FIG. 5 is a vertical section taken along line 5 --5 in FIG. 4 showing thelink guide member pivoted to the bridging position thereof; and

FIG. 6 is a perspective view of one of the link guide members.

As shown in the drawings and morefully explained in US. Patent Nos. 3,181,423 and 3,182,555, the gun to which the present invention is particularly applicable is provided with a receiver 12 having a forwardly opening bore 14 therein for slidably receiving the breech end portion of a barrel 16. A drum 18 is rotably mounted between a pair of spaced supports 19 projecting outwardly from receiver 12 and is adapted to be operated by a variable output motor 20 suitably mounted to the rear drum support. Although drum 18 is depicted above receiver 12 in FIG. 1, it should be understood that the gun is equally operable regardless of the particular orientation thereof relative to the ground or the platform on which it may be mounted. The exterior periphery of drum 18 is formed with a continuous cam track 22 for slidable engagement with a cam follower 24 extending upwardly from a rectangular lug 25 extending along the breech end of barrel 16. Thus, whenever drum 18 is rotated by motor 20, barrel 16 is longitudinally reciprocated to open and close the breech. A second cam track 26 is disposed in the rear face of drum 18 and serves to reciprocate a feed lever 27 with a pawl 28 pivoted to the free end thereof for intermittently advancing a flexibly linked belt of cartridges 30 into a substantially rectangular feedway 32 extending transversely through receiver 12.

Feedway 32 is longitudinally positioned in receiver 12 so that the rear endwall thereof is disposed beyond the terminus of the rearward stroke of barrel 16 for a purpose to be shown. A cartridge guiding channel 34 is formed in the floor of feedway 32 adjacent the rear endwall thereof and of sufficient width to slidably receive a portion of the annular rim 36 on each cartridge 30 in the belt upon entry into feedway 32. At the entrance end of feedway 32, receiver 12 is suitably slotted, as best indicated at 38 in FIG. 2, to provide means for the coextensive attachment thereto of a feed tray 40 which is releasably retained in place by a spring-biased plunger 42 shown in FIG. 1. The roof of feed tray 40 is suitably slotted, as shown at 44, to provide for the reciprocating passage of feed pawl 28. A spring-biased pawl 46 is pivotally mounted in the floor of feed tray 40 and projects upwardly into the interior thereof to prevent retrograde movement of the cartridge belt during the stationary intervals thereof.

Each cartridge 30 is slidably encircled by a link 4-8 which is flexibly coupled to the link on the cartridge adjacent thereto by a connector 50 to form a continuous belt. Each link 48 is formed with opposing flats 52 which are sufficiently spaced apart to permit slidable passage through the rectangular interior of feed tray 40 and feedway 32 in receiver 12. Flats 52 are formed by overlapping the end portions of link 48 to provide a double wall section as best shown in FIGS. 2 and 5. In order to properly support the projectile end of cartridge 30 in chambering alignment wit-h the the bore of barrel 16, the

floor of feedway 32 is slightly elevated forwardly of the link passage area therein as best indicated at 54 in FIG. 3. Thus, as barrel 16 is returned to battery position, the breech end thereof fits smoothly over the tapered projectile end of cartridge 30 and continues rearwardly to -contact the edges of link flats 52 and force such link rearwardly along cartridge 30 out of connecting engagement with the link on the cartridge adjacent thereto. When barrel '16 reaches the rearwardmost position thereof, link 48. has been moved into abutment with the rim 36 of cartridge 30 as best shown in phantom in FIG. 3.

While the inclusion of flats 52 in the configuration of link 48 effectively prevents any tilting thereof in feed tray 40, such is not the case in feedway 32 in receiver 12 wherein the floor thereof is provided with a longitudinally xtending central trough 56 which serves to accommodate the peripheral contour of barrel 16. opposite trough 56, the ceiling of feedway 32 includes a longitudinally extending slot 58 which, as best shown in FIG. 2, provides a passage for rectangular lug 25 on Even if such cartridge 30 did move into alignment with the bore of barrel 16 without malfunction, the tilted orientation of the surrounding link 48 could interfere with the proper separation thereof from the link 48 on the adjacent cartridge 30 during the rearward movement imparted thereto by barrel 16.

However, these cartridge feeding difiiculties have been virtually eliminated by the present invention. As best shown in FIGS. 3 and 4, the level of the floor in feedway 32 is slightly lowered over a substantially square area 61 extending from the entry end thereof to a point just beyond trough 56 to accommodate a relatively thin sectorshaped link guide 62. The ceiling of feedway 32 is similarly formed to accommodate a second identical guide 62 in spaced relation opposite to the one in the floor of feedway 32. The smaller end of guide 62 is arcuately formed, as shown at 64, and is provided with a concentrically disposed mounting hole 66 therethrough adapted to rotatably fit over a cylindrical pin 68 fixedly secured in the entry end of feedway 32 by a suitable lock pin 69. Mounting pin 68 is formed with an enlarged circular head 70 of such diameter that substantially half of the circumferential periphery thereof is coextensive with the arcuate end 64 of guide 62 as best illustrated in FIGS. 3 and 4.

The larger end of guide 62 may be arcuately shaped or, as shown in FIG. 6, may be formed -by a series of successive angular cuts 74. In addition, a portion of such larger end of guide 62 is removed by an L-shaped cut, as shown at 76, in order to provide a linear contact surface 77 for barrel 16. A substantially rectangular lug 78 is provided on the flat surface of each link guide 62 adjacent pivot hole 66 therein and is formed with an arcuate side 80 concentric with the periphery of hole 66 and with circular head 7 t) of mounting pin 68.

When each link guide 62 is disposed in feedway 32 so In addition, directly that the linear portion thereof between arcuate end 64 and the start of angular cuts 74 is parallel to the corresponding exit edge of feed tray 40 as shown in FIG. 3, lug 78 is disposed in the path of the link 48 on the leading cartridge 30 in the belt. Thus, as such cartridge is advanced to the chambering position thereof, the leading end of flat 52 contacts the side of lug 73 on link guide 62 and pivots such guide inwardly in feedway 32 to the position shown in FIG. 4. In this position, the link guide 62 in the fioor of feedway 32 supports link 48 for passage therethrough across the shoulder formed by square area 61. At the same time, the link guide 62 in the ceiling of feedway 32 provides a bridge across slot 58 in receiver 12 which in combination with the guide 62 in the floor of feedway 32 cooperates with flats 52 on link 48 surrounding the leading cartridge in the belt to eiTectively prevent any tilting thereof.

As barrel 16 is actuated rearwardly after the leading cartridge in the belt moves into the chambering position thereof shown in FIG. 4 in engagement with a spaced pair of spring-biased pivotal latches 82 disposed in channel 34, the breech face of barrel 16 strikes contact surface 77 on each link guide 62 and simultaneously returns the guides to the original position in which lug 78 is disposed in the path of the link in feed tray 40 as shown in FIG. 3.

Since link guides 62 are. positively actuated in one direction by the link on the leading cartridge in the belt and in the opposite direction by the breech end of barrel 16, it is readily apparent that no springs are required, thereby eliminating the usual source of difliculty heretofore encountered in the various mechanisms utilized to guide and control a cartridge belt in the feedway of a high speed automatic gun. In addition, the utilization of the link guide members in the manner taught herein eliminates the former necessity for uninterrupted surfaces in the floor and ceiling of the transverse cartridge feedway through the receiver and consequently permits the utilization of a noncylindrical contour at the breech end of the reciprocating barrel without a compensating increase in the height of the feedway opening. Furthermore, since the feeding movement of the cartridge belt and the reciprocation of the barrel is not affected by the particular mounting orientation or firing attitude of the gun, link guides 62 are always actuated in the same positive fashion regardless of the position in which the gun is being operated.

The present invention has been described in detail above for the purpose of illustration only and is not intended to be limited by this description or otherwise except as defined 'by the scope of the appended claims.

I claim:

1. In an automatic gun having a receiver including a rectangular feedway extending transversely therethrough for the passage of a linked belt of cartridges, a barrel slidably mounted in the receiver for reciprocal longitudinal movement from and toward a fixed point adjacent the rear endwall of the cartridge belt feedway, and means for advancing the cartridge belt into the feedway in synchronism with the reciprocal movement of the barrel to position the leading cartridge in the belt in chambering alignment With the barrel, the improvement comprising a pair of linkguide members pivoted at opposite locations in the feedway adjacent the entrance end thereof, and a lug projecting from each of said link guide members into the feeding path of the link on the leading cartridge in the belt whereby said guide members are pivoted thereby into position to restrain the link on the leading cartridge from tilting in the feedway during the movement thereof into chambering alignment with the barrel.

2. The combination defined in claim 1 including means for mounting said guide members in the feedway to provide the same distance therebetween as that between the remaining portion of the feedway in order to slidably receive the link on the leading cartridge in the belt with the same uniformity throughout the transverse extent of the feedway.

3. In an automatic gun having a receiver with a rectangular opening extending transversely therethrough to form a feedway for the passage of a linked belt of cartridges, a cylindrical barrel slidably mounted in the receiver for reciprocal longitudinal movement from and toward a fixed point adjacent the rear endwall of the cartridge belt feedway, means in the feedway opening for accommodating the periphery of the breech end of the barrel, and means for advancing the cartridge belt into the feedway in synchronism with the reciprocal movement of the barrel to successively position each leading cartridge in the belt in chambering alignment with the barrel, the improvement of means for restraining the link on the leading cartridge in the belt against tilting in the feedway during the movement thereof into chambering position, comprising a pair of link guide members pivoted at opposite locations in the feedway adjacent the entrance end thereof, the feedway opening in the receiver having upper and lower wall surfaces with recess areas therein communicating with the entrance end thereof for seating said guide members at a depth equivalent to the thickness thereof whereby the spacing therebetween is equivalent to the distance between the remaining portion of the feedway opening for providing uniform slidable reception of the link on the leading cartridge, a lug projecting from each of said link guide members into the path of the link on the leading cartridge in the belt whereby said guide members are pivoted thereby to form an uninterrupted path for the passage of the link as the cartridge therein is advanced into chambering alignment with the barrel, and an L-shaped cutout portion in each link guide member defining an edge adapted to be disposed in the rearward path of the barrel at the conclusion of the pivotal movement imparted to said link guide members by the link on the leading cartridge whereby said guide members are pivoted by the barrel to return to the position in which said lugs thereon are disposed in the path of the link on the leading cartridge.

4. In an automatic gun having a receiver with a rectangular opening extending transversely therethrough to define a feedway for the slidable passage of a linked belt of cartridges, a cylindrical barrel having a locking lug projecting upwardly from the breech end thereof, the barrel being slidably disposed in the receiver for longitudinal movement from and toward a battery position adjacent the rear endwall of the cartridge belt feedway, and means for advancing the cartridge belt into the feedway in synchronism with thereciprocal movement of the bar-- rel to successively position each leading cartridge in the belt in chambering alignment with the barrel, the combination of, a floor surface in the feedway having a centrally disposed arcuate trough extending longitudinally therealong to accommodate the peripheral underside of the breech end of the barrel, a ceiling surface in the feedway having a longitudinally extending rectangular slot therethrough for the passage of the locking lug on the barrel, said floor and ceiling surfaces in the feedway having substantially square recessed areas extending therein from the entrance end of the feedway, a relatively fiat guide member pivotally secured adjacent one end thereof in each of said recessed areas for pivotal movement between an outer position in the path of the link on the leading cartridge in the belt and an inner position in the path of the barrel during the return thereof to battery position, a lug projecting from each of said guide members into position for engagement by the link on the leading cartridge during the feeding movement of the belt into the feedway whereby said guide members are simultaneously pivoted intothe feedway to bridge said arcuate trough and said rectangular slot therein and provide uninterrupted support for the link on the leading cartridge during the movement 'of the latter into chambering position, and L-shaped cutout portion on one side of each link guide member for defining an edge adapted to be contacted by the breech end of the barrel during the return thereof to battery position whereby said link guide members are pivoted outwardly thereby to position said lugs thereon for contact by the link on the next successive leading cartridge,

5. The combination defined in claim 4 including a feed tray having a rectangular opening therethrough for the passage of the cartridge belt, means for releasably securing said feed tray to the side of the receiver in longitudinal coextensive relation with said feedway opening therein, said feed tray opening being of slightly smaller height than the corresponding dimension of the feedway to provide surfaces for halting the pivotal movement imparted to said guide members by the return of the barrel to battery position.

References Cited by the Examiner SAMUEL FEINBERG, Primary Examiner.

S. C. BENTLEY, Assistant Examiner. 

1. IN AN AUTOMATIC GUN HAVING A RECEIVER INCLUDING A RECTANGULAR FEEDWAY EXTENDING TRANSVERSELY THERETHROUGH FOR THE PASSAGE OF A LINKED BELT OF CARTRIDGES, A BARREL SLIDABLY MOUNTED IN THE RECEIVER FOR RECIPROCAL LONGITUDINAL MOVEMENT FROM AND TOWARD A FIXED POINT ADJACENT THE REAR ENDWALL OF THE CARTRIDGE BELT FEEDWAY, AND MEANS FOR ADVANCING THE CARTRIDGE BELT INTO THE FEEDWAY IN SYNCHRONISM WITH THE RECIPROCAL MOVEMENT OF THE BARREL TO POSITION THE LEADING CARTRIDGE IN THE BELT IN CHAMBERING ALIGNMENT WITH THE BARREL, THE IMPROVEMENT COMPRISING A PAIR OF LINK GUIDE MEMBERS PIVOTED AT OPPOSITE LOCATIONS IN THE FEEDWAY ADJACENT THE ENTRANCE END THEREOF, AND A LUG PROJECTING FROM EACH OF SAID LINK GUIDE MEMBERS INTO THE FEEDING PATH OF THE LINK ON THE LEADING CARTRIDGE IN THE BELT WHEREBY SAID GUIDE MEMBERS ARE PIVOTED THEREBY INTO POSITION TO RESTRAIN THE LINK ON THE LEADING CARTRIDGE FROM TILTING IN THE FEEDWAY DURING THE MOVEMENT THEREOF INTO CHAMBERING ALIGNMENT WITH THE BARREL. 